1. Field of the Invention
This invention relates generally to solar collector systems, and more particularly to solar collector systems that include sandwich core structures.
2. Description of the Related Art
Recent economic and political developments have resulted in a drastic increase in the cost of conventional energy sources such as crude oil, natural gas and the like. Due to the increased prices of conventional energy sources and because of the very real and potential shortages of conventional energy sources such as crude oil, natural gas and the like, many alternative sources of energy are being investigated. One particularly promising alternative source of energy is the recovery and use of solar radiation or “solar energy”. While it has long been known that solar energy is a vast, untapped source of energy, conventional energy sources such as crude oil, natural gas and the like, have been so cheap that solar energy recovery could not be justified from an economic standpoint. Now, because of the changing economic conditions affecting conventional energy and because of possible shortages of such conventional energy, solar energy represents a viable source of energy.
Many types of solar collector systems have been investigated. Such solar collector systems include tubes, mats and other large surface area solar collectors that contain some type of working fluid that is heated by merely placing such large solar collectors in the sun. Such solar collectors are effective in heating the working fluids only a few degrees above ambient temperature. Additionally, such large solar collectors are relatively expensive.
The use of highly reflective surfaces or mirror-type surfaces are very effective for gathering solar radiation striking a relatively large effective area and focusing or concentrating the radiation onto a relatively small target area or energy receiver. Such types of solar collectors include a collection of many individual flat mirrors that can be focused onto one small target or energy collector, as well as various types of curved and shaped reflective surfaces that will focus the collected solar energy onto a relatively small surface or energy receiver.
One particularly preferred type of solar collector is a parabolic reflector which will gather solar radiation and reflect the radiation onto a small target or energy receiver which is located at the focal point of the parabola. Because of the relatively high cost of constructing a true parabolic surface, parabolic reflectors are not widely used for low cost energy recovery from the sun.
Trough-like reflectors have been investigated as relatively low cost types of solar collectors. The trough-like reflectors have proven to be much less expensive to manufacture than true parabolic reflectors. Some of the most effective trough-like reflectors utilize a relatively large reflector surface that is formed by constructing an elongated trough-like device with the walls of the trough having a constant parabolic shape whereby the focal point of the parabolic trough lies along a relatively straight line above the trough. Thus, the concave trough-like solar collector can be equipped with a target or energy receiver that is disposed along the line formed by the focal point of the parabolic reflector. By using such a reflector, solar radiation which strikes the concave surface of the solar collector will be reflected and concentrated onto the focal point of the parabola and can be captured by an energy receiver located at or near the focal point of the parabolic surface.
There is a need for improved solar collector systems that are more cost effective, are easier to install, can be installed in a variety of different locations and have lower weight that eliminates or reduces the need for frames, ribs and the like. With the present invention, the structure is sufficiently strong that it does not need additional support elements.